/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.util;

import java.io.InputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.lang.reflect.Proxy;

/**
 * Custom subclass of <code>ObjectInputStream</code> that loads from the class
 * loader for this web application. This allows classes defined only with the
 * web application to be found correctly.
 * 
 * @author Craig R. McClanahan
 * @author Bip Thelin
 * @version $Id: CustomObjectInputStream.java 939353 2010-04-29 15:50:43Z
 *          kkolinko $
 */

public final class CustomObjectInputStream extends ObjectInputStream {

	/**
	 * The class loader we will use to resolve classes.
	 */
	private ClassLoader classLoader = null;

	/**
	 * Construct a new instance of CustomObjectInputStream
	 * 
	 * @param stream
	 *            The input stream we will read from
	 * @param classLoader
	 *            The class loader used to instantiate objects
	 * 
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	public CustomObjectInputStream(InputStream stream, ClassLoader classLoader)
			throws IOException {

		super(stream);
		this.classLoader = classLoader;
	}

	/**
	 * Load the local class equivalent of the specified stream class
	 * description, by using the class loader assigned to this Context.
	 * 
	 * @param classDesc
	 *            Class description from the input stream
	 * 
	 * @exception ClassNotFoundException
	 *                if this class cannot be found
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	public Class resolveClass(ObjectStreamClass classDesc)
			throws ClassNotFoundException, IOException {
		try {
			return Class.forName(classDesc.getName(), false, classLoader);
		} catch (ClassNotFoundException e) {
			try {
				// Try also the superclass because of primitive types
				return super.resolveClass(classDesc);
			} catch (ClassNotFoundException e2) {
				// Rethrow original exception, as it can have more information
				// about why the class was not found. BZ 48007
				throw e;
			}
		}
	}

	/**
	 * Return a proxy class that implements the interfaces named in a proxy
	 * class descriptor. Do this using the class loader assigned to this
	 * Context.
	 */
	protected Class resolveProxyClass(String[] interfaces) throws IOException,
			ClassNotFoundException {

		Class[] cinterfaces = new Class[interfaces.length];
		for (int i = 0; i < interfaces.length; i++)
			cinterfaces[i] = classLoader.loadClass(interfaces[i]);

		try {
			return Proxy.getProxyClass(classLoader, cinterfaces);
		} catch (IllegalArgumentException e) {
			throw new ClassNotFoundException(null, e);
		}
	}

}
